Wilting and drying up of the tillers or the whole plants accompanied or not by leaf necrosis; no growth of new shoots after mowing; yellow stripes turn necrotic along the leaf; distorted growth of the leaves out of the sheath or difficulty of cobs (ears, heads) to emerge; young leaves have a pale colour.

In the Lolium multiflorum yellow droplets form inside the hollow of the stem.

Bacterial wilt settles in the xylem vessels. The disease can only settle through lesions from which it extends to the xylem. It goes counter sap-flow down to the base of the plant and infects the neighbouring tillers.

Considerable damage may occur after long periods of hot and dry weather, while in cool and wet periods hardly any diseased plants are found. The pathogen may be identified by isolation and biochemical tests. Specific antibodies used in immunofluorescence and ELISA had a high degree of sensitivity and specificity against the target bacterium. The two methods were used for screening pure cultures and detecting bacteria directly in plant tissue extracts. Their application revealed the presence of low numbers of bacteria in symptomless plants and a discontinuous distribution within the plant.

Cultures of Xanthomanas campestris pv graminis showed no loss of virulence following freeze-drying and revival.

Inoculation of seeds, and inoculation of plants for seed production, X. campestris pv. graminis was shown to be seed-transmitted. The level of infection in seeds was, however, too low to produce plants with disease symptoms.

The spread inside the crop is caused by the infected cutter bar of forage harvesters which can carry the pathogen for several months.

The Genebanks

Sign up to our

Newsletter

Thank you

close-icon

The CGIAR Genebank Platform enables CGIAR Research Centers to fulfill their legal obligation to conserve and make available accessions of crops and trees on behalf of the global community under the International Treaty on Plant Genetic Resources for Food and Agriculture.